How to Know If You’re Getting Too Much Fiber

There are many reasons why fiber is good for you, including its ability to lower cholesterol and reduce the risk of colon cancer.

But eating too much fiber may also cause problems. This is especially true if you start eating a lot of fiber when your body isn’t used to it. So, how do you know how much fiber is too much? 

Read on to learn how much fiber you need, and what symptoms might mean you’re getting too much. 

What happens if you eat too much fiber?

Fiber is an indigestible type of carbohydrate found in plant foods. This means that it stays mostly intact as it passes through your digestive tract. 

To understand how your body responds to too much fiber, it helps to know that there are two types of fiber: soluble fiber and insoluble fiber. 

Soluble fiber dissolves in water. It can help manage constipation by softening hard stools. It may also help with diarrhea since it can firm up loose stools.

Insoluble fiber doesn’t dissolve in water. It increases stool volume, which helps stimulate your colon. Like soluble fiber, this can help manage constipation. However, since it doesn’t absorb water, it won’t help with loose stools. 

So, if you eat too much fiber — insoluble or soluble — your digestive tract may have a hard time moving food through. This can cause abnormal bowel habits and other abdominal symptoms. 

This is true whether you take in too much fiber from food, or from supplements like Metamucil, which contains soluble fiber. 

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• Best and worst foods for IBS: Certain foods can worsen symptoms of irritable bowel syndrome (IBS), while others can improve them. With time, you can figure out which foods work best for you.

Signs and symptoms of eating too much fiber

Eating too much fiber affects people differently. Some people may experience many symptoms, while others experience none. People who have a digestive condition — such as irritable bowel syndrome (IBS) — or those who aren’t used to eating a lot of fiber may be more sensitive to large amounts of fiber in their diet. 

Here are some of the symptoms of too much fiber.

Gas

Gas is a common symptom for people who consume high amounts of fiber. Gas occurs as a result of fermentation, the process by which your gut bacteria processes fiber. You may feel gassy after eating certain high-fiber foods (like beans), or meals with higher fiber content than what you’re used to. 

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Both types of fiber can lead to gas, but soluble fiber may be more likely to cause this symptom. This is because soluble fiber gets fermented by your gut bacteria, whereas insoluble fiber resists fermentation. 

Bloating

Often gas and bloating go hand in hand. When you have gas, air gets trapped in your digestive tract. This can lead to feelings of pressure or discomfort.

Diarrhea

Insoluble fiber increases the rate at which food moves through your digestive tract. This is the opposite of soluble fiber, which slows down this rate. Eating too many foods high in insoluble fiber may irritate your gut and lead to loose or frequent stools. 

Constipation

Fiber is often recommended as a way to help manage constipation, since not getting enough fiber can lead to constipation. But the opposite is also true. Since fiber adds bulk to your stool, too much fiber may cause your stool to become too bulky and difficult to pass. This may lead to constipation.

Abdominal pain

Abdominal pain and/or cramping is a common symptom of eating too much fiber, and often comes alongside bloating, diarrhea, or constipation. 

Nausea

Nausea can be a symptom of too much fiber. If you have a lot of gas or bloating, it’s possible to develop nausea as a result. Nausea should subside as the other symptoms improve. 

Feeling too full

One of the many benefits of fiber is that it helps you feel satisfied and full after eating. But if you consume too much fiber, you may feel uncomfortably full very quickly. 

Dehydration

Both insoluble and soluble fiber pulls water in from your digestive tract. So if you’re eating a lot of fiber but not drinking enough fluids, it can lead to dehydration. That’s why it’s important to drink enough water when eating a high-fiber diet. 

Bowel obstruction

While it’s not really a symptom, bowel obstruction is a serious but rare effect of too much fiber. It occurs when there’s a blockage in either the small or large intestine. It can occur in people who eat a very high-fiber diet but don’t consume enough fluids. 

What happens in bowel obstruction is that fiber creates bulk in the stool. If it forms a large mass, this may create a blockage. 

This is more likely to occur in people who have a narrowed bowel, such as those with Crohn’s disease or a history of bowel surgery. People at risk for bowel obstruction may be advised to limit their fiber intake. 

How much fiber do you need per day?

The FDA set the daily value for dietary fiber at 28 g per day, assuming a 2,000 calories per day diet. However, the amount of fiber you need will vary based on your age and sex.

Here are the fiber recommendations for adults according to the Dietary Guidelines for Americans:

• Women ages 18 to 50 years: 25 g to 28 g per day

• Women ages 51 and older: 22 g per day

• Men ages 18 to 50 years: 31 g to 34 g per day

• Men ages 51 and older: 28 g per day

The recommended amount lowers a bit with age because as you get older, metabolism and appetite also decrease. So, too much fiber may cause fullness and bloating in older adults, which can affect overall nutrient intake.

Note that some people may be able to eat higher amounts of fiber without any issues. So there isn’t a clear amount of fiber that’s considered “too much.” However, some research has reported that consuming over 50 g per day is more likely to cause symptoms of too much fiber. 

Remember that getting too much fiber is rare, especially in the U.S. Research suggests that only about 5% of adults in the U.S. meet their recommended fiber intake. In fact, the average fiber intake is only about 14 g per day. This is a public health concern, given what experts know about the health benefits of fiber. 

Foods that are high in fiber

Only plant-based foods contain fiber, and most provide a mixture of soluble and insoluble fiber. Food from animal sources contains no fiber.

There are five major plant food groups that provide fiber. These include:

• Fruits: All fruits — such as bananas, berries, and citrus fruits — provide fiber in some amount.

• Vegetables: Artichokes provide some of the most fiber per serving, while other veggies like kale provide the least. Nonetheless, all vegetables can help contribute to your daily fiber intake.  

• Whole grains: Brown rice, oats, and products made with whole wheat flour are examples of whole grains. Eating whole grains on their own or as an ingredient in another food is a great way to increase your fiber intake.

• Nuts and seeds: From almonds to pistachios to chia seeds, all nuts and seeds are an excellent source of fiber. 

• Beans and other legumes: Legumes, such as black beans and lentils, can provide almost 10 g of fiber per ½ cup serving. This is why eating beans is a great way to meet your daily fiber needs. 

Given that these plant-based foods are such good sources of fiber, it’s easy to see how eating a plant-based diet helps with fiber intake. And it may explain why vegans and vegetarians tend to eat more fiber than other people.

How to relieve symptoms of too much fiber

Symptoms of too much fiber can be very uncomfortable. The good news is there are a few things you can do to find relief.

Increase fiber consumption slowly

One reason why some people experience symptoms from too much fiber is that they increase their fiber intake too quickly. But the digestive system needs time to adjust to increased fiber. It may take your gut bacteria a few days to adapt to feeding on fibrous foods. 

So, rather than switching to high-fiber foods in all your meals at once, it’s better to increase gradually. Start with increasing fiber in one meal or snack, and increase slowly from there. 

Drink more water

Water supports the normal digestion process. So, drinking more water may help prevent and/or manage the symptoms and effects of too much fiber, such as constipation, dehydration, and bowel obstruction. 

Exercise

Moderate exercise helps digestion. Research suggests that exercise can improve symptoms of bloating and gas by keeping things moving in your digestive tract. When you exercise, your body also burns energy, which can provide relief from feeling overly full. 

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Written by:

Joanna Foley, RD

Joanna Foley, RD, is a registered dietitian (RD) and the owner of joannafoleynutrition.com, a private nutrition consulting business. She has previously worked as a clinical dietitian and outpatient renal dietitian.

Edited by:

Meredith Hoffa

Meredith Hoffa is a senior health editor at GoodRx, where she leads journalists and clinicians covering various well-being topics, particularly in diet and nutrition.

Reviewed by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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